The president called for the combined measles, mumps and rubella (MMR) vaccine to be split into separate shots, despite decades of research showing that the MMR vaccine is safe and effectivePresident Donald Trump issued an executive order on Monday aimed at altering the U.S. childhood vaccine schedule. The order would nix the current combined measles, mumps and rubella (MMR) vaccine in favor of giving a shot for each disease individually. Overwhelming evidence shows that the MMR vaccine is both safe and effective, with a low risk of adverse events. The order directs federal agencies to classify childhood vaccines into three categories: vaccines recommended for all children; vaccines “recommended for certain high-risk groups or populations”; and immunizations given “based on shared clinical decision-making.” The order is the Trump administration’s latest attempt to overhaul and curtail the childhood vaccine schedule.